The Effects of Salt Water On Willie Robertson
H. Abruzzo, N. Batmandakh, M. Becker, D. Holmes
AP Biology, Period 3
Miramonte High School, Orinda, CA
Abstract
This experiment tests the effect of salt water on the growth of chia plant on Chia® Willie. We predicted that a high concentration of salt water for watering the plant will slow the growth of chia plant. Ultimately, we learned that a high concentration of salt water actually kills the chia plant but a minimal concentration of salt water does slow the growth, verifying our hypothesis.
Introduction
Chia Pets, the kitschy knick-knacks that have been sprouting across America since their invention in 1977, are terracotta figurines with hollow insides and rows of tiny grooves. The hollow inside is meant to contain water (which is used to help grow the chia) and the tiny grooves serve as perches for the moistened chia seeds to grow. Chia Pets are well-known for their ability to grow and mature quickly, with the chia plant becoming mature within a week. (Edwards)
The chia plant is scientifically known as Salvia Hispanica and is of the Lamiaceae family. It is of North and Central American origin (specifically Mexico and Guatemala) and is of economic importance due to its uses in food additives as flavoring, in human food as a beverage base, and in homeopathic medicine as a folk treatment for various illnesses (USDA, Germplasm Resources Information Network). The seeds are full of Omega-3 fatty acids, protein, fiber and antioxidants (USDA, National Nutrient Database for Standard Reference), allowing beverages featuring chia seeds to become popular in health-foods stores.
The Chia Pet proved to be an ideal vessel to host our experiment, mainly because of their ability to grow chia plants rapidly and reliably, but also because it facilitated the measurement of our independent variable, the weight and height of the plants. The height of the plants was easily measured using a ruler during their time growing upon the Chia Pet, and were able to be quickly scraped off (as opposed to being uprooted from the soil) from the Chia Pet for ease of weighing.
Due to the economic value of chia, it is in the best interests of a chia grower to maximize his harvests. Thus, environmental factors (such as salinity) should be examined for their potential effects on chia plant growth. We hypothesized that because salt inhibits the uptake of water into plants (Munns), the higher the concentration of salt, the slower the chia plant would grow.
Materials
73.05g Kosher Salt (Diamond Crystal) (1 ¼ mol)
2.3 kg electronic scale (Oxo)
triple beam scale (the chem room) We actually used the electronic one, will get deets tomorrow
44g tupperware container (stays fresher longer)
4 DuckDynasty “Chia Willie” Chia Pets
4 1 gal Arrowhead distilled water
4 7 oz porcelain container (le creuset)
1 50ml measuring spoon (The Pampered Chef)
1 L measuring cup (Fire King)
1 cup measuring cup (Pyrex)
1 5 ml medicine spoon (Long Drugs)
5 large bowls (large enough to cover the Chia Pets)
4 9.8mL of chia seeds
4 plastic trays
4 plastic shopping bags
4 plastic ziploc bags
1 plastic funnel
1 mm ruler
1 pitch black dark environment (Hanna’s closet)
4 small spoons
1 incubator (GET INFO ON INCUBATOR) (I can look at this in class tomorrow)
Procedure
1. Measure 58.44g of NaCl into the tupperware container and add to a bowl
2. Measure 1L of distilled water in 1 L measuring cup and add to the bowl from step 1
3. Mix well until NaCl is dissolved (this is the stock solution).
4. Measure 300mL of stock solution with 1L measuring cup (using NaCl solution from above) and add to Large Bowl1
5. Measure 2.7L of distilled water and add to LargeBowl1
6. Place Chia Pet 1 into LargeBowl1 for 1 hour (Fig. 2).
7. Measure 600ml of stock solution with 1L measuring cup and add to Large Bowl2
8. Measure 2.4L of distilled water and add to LargeBowl2
9. Place Chia Pet 2 into Large Bowl 2 for 1 hour (Fig. 3).
10. Measure 2 x3 L of distilled water and add to Large Bowl 3 and Large Bowl 4
11. Place Chia Pet 3 into Large Bowl 3 for 1 hour (Fig. 4) and place Chia Pet 4 into Large Bowl 4 for 1 hour.
12. Make a new stock solution of 14.61g NaCl and .5L of distilled water
13. Measure 1 mL of stock solution and add to small porcelain cup 1
14. Measure 49mL of distilled water into porcelain cup 1
15. Measure 2 mL of stock solution and add to small porcelain cup 2
16. Measure 48mL of distilled water into porcelain cup 2
17. Measure 2 x 50mL of distilled water into porcelain cup 3 and porcelain cup 4
18. Measure 4 x 9.8mL of chia seeds and place each quantity into a porcelain cup.
19. Let the porcelain cups sit for 1 hour, stirring with the spoons every 5 minutes.
20. After the chia pets have been soaking for 1 hour, remove them from their solutions and place each into a tray (Fig.7).
21. Removed seeds from cup 1 and spread onto the ridges of Chia Pet 1 using the small spoon
22. Repeat step 21 for each of the respective chia pets.
23. Place the chia pets in a window (except for chia pet 4, which should be placed in a completely dark environment) and cover with plastic shopping bags for first four days
24. Every night at 9 PM, use millimeter ruler to measure the height of each of the chia plants at 3 specific locations on Willie’s beard (the center front of the beard, the top of the head, and underneath the bandanna behind his head) and record, as well as “water” each chia pet with its specific concentration of NaCl solution until the ceramic pet is filled to the brim.
25. After 9 days, scrape chia plants off of Willie’s faces and into 4 plastic ziploc bags.
26. Place the bags into the freezer overnight.
27. Incubate the chia plants for 24 hours.
28. Weigh the chia plants on the Oxo electronic scale and record.
29. Dispose of chia pets and willie’s dreams of becoming a real boy.
NOTE: when we mixed the chia seeds, the one soaked in water was mushier than the ones soaked in salt water. (Fig.5).
Images of Setup
Fig.1: Chia Pets with Fig.2: Chia Pet 1 and Fig.3: Chia Pet 2 Fig.4: Chia Pet 3 and Fig.5: The seeds
packs of seeds. its seeds soaked in and seeds soaked seeds soaked in 3L on the left look a lot
300 mL stock solution. in 600 mL stock distilled water. more clear than
solution. the seeds on
the right.
Fig.6: Water Chia pets by filling the Chia with the respective solutions through the hole.
Fig.7: Chia Pets placed on trays after their soaking/bath.
Fig. 8: Chia Pets, covered in seeds, are placed in front of a large window to expose to sunlight. 
Fig. 9: Chia Pets are facing the window so that their beards can grow in the next couple of days. Do not move Chias from the spot!
Fig 10: The closet chia on scrape day. Note the mold on the back side.
Fig 11: The closet chia developed a considerable amount of mold, as seen here
Fig 12: .1 mol/L NaCl solution chia pet (day 5)
Fig 13: .2 mol/L chia pet (day 5)
Fig 14: distilled water chia (day 5)
Fig 15: Delicious mold grows peacefully on the .2 M solution chia pet (Day 9)
Results
day
|
height of chia 1 (.1 M) mm
|
height of chia 2
(.2 M) mm
|
height of 3
(water)mm
|
height of chia 4
(closet and water) mm
|
1
|
0
|
0
|
0
|
0
|
2
|
0
|
0
|
0
|
0
|
3
|
germination
|
0
|
germination
|
0
|
4
|
2.0, 1.0, 2.0 avg(1.7)
|
germination
|
6, 2, 4
avg(4.0)
|
0
|
5
|
1, 1, 2 avg(1.3)
|
0, 0, 1 avg(0.3)
|
10, 5, 15
avg(10.0)
|
0
|
6
|
3, 1, 1 avg(1.7)
|
1, 0, 0 avg(0.3)
|
8, 11, 13
avg(10.7)
|
0
|
7
|
4, 1, 4 avg(3.0)
|
mold
|
10, 13, 20
avg(14.3)
|
0
|
8
|
4, 1, 7 avg(4.0)
|
dead
|
13, 15, 25
avg(17.7)
|
germination
|
9
|
6, mold, 7 avg(4.3)
|
dead
|
19, 18, 26
avg(21.0)
|
3, 2, 1.5
avg(2.2)
|
10
|
6, mold, 6 avg(4.0)
|
dead
|
14, 20, 34
avg(22.7)
|
7, 10, 4
avg(7.0)
|
*
Our results were clear: salinity affects the growth of chia pets. The pets in a water of .1M NaCl concentration germinated on day 3, and grew at a relatively constant rate of .32 mm/day. The pets grown in a water of .2M achieved germinated on day 4, grew .3 mm, and ceased growing. In contrast, the control germinated on day 3 and grew at a rate of 3.2mm/day, ten times faster than the chia in .1M. Lastly, the closet chia germinated on day 8, and grew at a rate of 3.5mm/day. Both the .2M chia and the closet chia experienced copious amounts of mold growth, as seen in figures 10 and 11.
Discussion
This experiment was designed to measure the effect of salt water on the growth of chia plants. Our hypothesis was that a higher concentration of salt would slow the growth, maybe even destroy the plant.
As shown in Fig. 13 the Chia Pet watered with .2 M of salt water has barely germinated by day 5 and grew to be as tall as 1 mm. In contrast, the chia pet watered with only .1 M of salt water actually grew to be as tall as 2 mm on the fifth day (see fig. 12) and in the end, weighed about (INSERT MASS OF .1M CHIA). In contrast, the Chia Pet watered with just distilled water grew to be as tall as 15 mm on the fifth day and the plant weighed about (INSERT MASS OF WATER CHIA) in the end. One noteworthy fact is that the closet chia, that was not exposed to light, actually grew to be as tall as 10 mm on the tenth day and weighed about (INSERT MASS OF CLOSET CHIA).
These results validate our hypothesis that as the concentration of salt water increase, the growth of the chia plant decrease -- and in some cases destroy the plant. The data also shows that the chia plant can tolerate moderate salinity suggesting that small amount of salt is not detrimental to growth. The reduced plant growth due to salinity are often associated with decreases in photosynthetic activities. This further the point that certain concentration of salinity can inhibit photosynthesis, as demonstrated by the Chia Pet watered with .2M of salt water (Allakhverdiev). The salt had an ionic and osmotic effect that reduced the size of the chia plant.
Error Analysis
In our experiment, the most crucial variable was the salt concentration. In order to prevent evaporation in our solutions over time, thereby making solutions with higher salinities, we covered each plant’s specifically concentrated solution with plastic wrap, and always made sure salt was dissolved to prevent lower concentrations in the solution for watering.
However, concentration alteration probably did take place in the actual chia head, as well as in the shallow wide drip tray it was placed in. The way the chia pet grows is through the moisture in the clay , so the solution growing the plant is directly affected by both the water inside the head (where water was poured every night) as well as where that water comes out at the bottom into the drip tray, mixed in with the seeds that have fallen off the clay structure. Since this water was exposed to open air at all times, water loss in the head cannot just be attributed to the ongoing photosynthesis of the plant; evaporation most likely occurred. With the evaporation of water, salt remains, and more salted water is added. Thus, the concentration of salt increases with every watering. This is probably a significant factor in how quickly and to what extent our .2 mol/L solution chia plants died and decayed, even though it was under the .3 mol/L limit for semi salt-resistant plants similar to the chia (Mustapha, Gasmi, and Neffati). A reason we hadn’t compensated for evaporation was that it was not a factor at all in the control chia grown with distilled water.
In a follow up experiment, one way to keep concentration levels more consistent would be, when watering the plants, to remove all previous water in chia head and drip tray, and replace with full amounts of precisely concentrated solutions. However, this still wouldn’t account for any absorbed solution inside the clay structure, presenting a fault in using the chia pet model. Also, slight evaporation could occur as the day progresses.
Another issue in experimental design that potentially exaggerated the effects of high NaCl concentration was watering time. In order to have consistent measuring times, we measured and watered the plants at 9 pm. However, this meant that the water level was decreasing and flowing into the drip tray for an extended period of time without any photosynthesis occurring. By the time photosynthesis could start, the water necessary for photosynthesis would be entirely absent for the highest sections of the plant. This is another problem with using the chia pet: water exposure is different for different heights on the clay structure.
While it could be argued that this error was not crucial, it was in the case of solute dissolved in water. Since a NaCl .1 M is not the same concentration as inside the plant cells, osmosis is occurring, meaning that water is being pumped out of the cells in order to maintain equilibrium with it’s .1 M surroundings. Even more water is then required in order to prevent the total dehydration of the cell. This assumption is supported by our experiment, in which, every night, it took less water to fill the top of the control chia pet than the salted plants (until the .2 mol/L died).
So, with the water level reset at night, the dehydrating effects of the salt were greatly accentuated. Together, this accounts for the consistent data measuring longer chia height on the front lower side of the chia pet and back lower side of the chia pet versus the very top of the chia pet, especially explaining (although it is only partially contributing to it) the complete stop in growth on the top of the .1 mol/L chia pet.
Regarding data/experimental errors, the .2 mol/L chia pet was especially difficult to manage. The copious mold growing on it made almost impossible to harvest and incubate in order to obtain a dry mass measurement. Therefore, we only have data for its height. In a future experiment, a better method would be to immediately incubate and weigh this plant as soon as signs of its death were certain.
Speaking of mold, it was a factor that also contributed to mass data collected in the .1 mol/L chia pet as well as the closet chia pet. While we made our best efforts to scrape off mold, it was still an addition of mass. It also had a decaying effect on the seeds before the mold was removed, so mass might have decreased as well, resulting in a twice altered mass.
Another error pertaining to mass was the initial spreading of seeds on the chia pets. Because of the different salinities, the salt-water-chia solutions had varying viscosities. This made spreading and distribution of seeds more inconsistent, and while the amount of seeds was meant to be the same for all plants, many seeds were so slippery that they dropped into the drip tray and were unsalvageable, making the seed mass different from the start, affecting the dry mass of the plants later.
As always, human and equipment error are always factors in an experiment. Potentially noteworthy factors in this case are that the ruler used to measure the closet chia was different the ruler used to measure the height of the other three plants. Also, the scale on which the NaCl was measured was not precise enough to exactly calculate one mol, so some concentration errors could stem from there.
Citations
Allakhverdiev, Suleyman I, et al., comps. Ionic and Osmotic Effects of NaCl-Induced Inactivation of Photosystems I and II in Synechococcus. N.p.: Plant Physiol, 2000. US National Library of Medicine National Institutes of Health. Web. 4 Dec.2013. <http://www.ncbi.nlm.nih.gov/pmc/articles/ PMC59068/>.
Edwards, Owen. "Chia Pet." Smithsonian.com. Smithsonian Magazine, Dec. 2007. Web. 04 Dec. 2013. <http://www.smithsonianmag.com/arts-culture/object-chiapet-200712.html?c=y>
R. Munns, 2002. “Comparative Physiology of Salt and Water Stress. Plant, Cell and Environment”, 25, 239-250.
Gorai, Mustapha, Hayet Gasmi, and Mohamed Neffati, 2011. "Factors Influencing Seed Germination of Medicinal Plant Salvia Aegyptiaca L. (Lamiaceae)." Saudi J Biol Sci 18: n. pag. 13 Feb. 2011. Web. 4 Dec. 2013.
USDA, Agricultural Research Service, National Genetic Resources Program.
Germplasm Resources Information Network - (GRIN) [Online Database].
National Germplasm Resources Laboratory, Beltsville, Maryland.
URL: http://www.ars-grin.gov/cgi-bin/npgs/html/family.pl?619 (04 December 2013)
USDA, Agricultural Research Service.
National Nutrient Database for Standard Reference. [Online Database].
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URL:http://ndb.nal.usda.gov/ndb/foods/show/3655?qlookup=12006&max=25&man=&lfacet=&new=1 (04 December 2013)
